I. Field of the Invention
The present invention relates generally to fluid handling devices and, more particularly, to a combination check valve and flow meter.
II. Description of the Prior Art
There are a number of previously known check valves which use a spring bias valve member to prevent reverse flow through the valve. Similarly, there are a number of previously known fluid flow meters which employ a variable area orifice for measuring the fluid flow rate. Many of these previously known fluid flow meters use a pivotal vane or tapered needle to vary the area of the orifice opening.
In the above-identified copending patent application, a combination check valve and fluid flow meter is disclosed. In some applications, however, dirt accumulation on the valve member or valve seat can result in false flow readings. Furthermore, an excessive back pressure can result in back flow leakage through the check valve.